Yet the rampaging growth to which the metropolis, in common with other American centers of population, has been subject during the past two or three decades means not only that these pleasant places are being pressed upon by many more people than anyone thought they would ever have to serve, but also that some of them are in danger of destruction or irreparable damage, and the tone of the city as a whole has been changing for the worse. The once magnificent upper estuary, as we have seen, is afflicted with complex and ugly pollution that shuts it off from the pleasant use it might otherwise sustain, and makes it a detraction from the Federal splendor along its northern shore rather than the enhancement it used to be. In places like the Alexandria and Georgetown waterfronts, industrial dilapidation on the shorelines more appropriately matches that pollution in mood, and on the Virginia side here and there undistinguished, often jerrybuilt highrise clutter has taken the place of the calm and wooded hills toward which the capital city once could look. Parks and open areas within the metropolis and out from it are often crowded, trampled, and belittered during most times when people can get away from making a living to visit them, and thus can furnish only a little of the quiet and elbow room that might be their main contribution to urban peace of mind. They are also subject to pressure and often damage from outside, stemming from the economics, the politics, the governing mood of restless growth. The blowtorch roar and black oily exhaust of jet airliners coming and going at National Airport, for instance, diminish and cheapen all the green space and monumental beauty so purposefully arranged along the Potomac shore. And only the bitterest kind of fight can occasionally save a park or a stream valley or the river itself from a projected addition to the spaghetti network of freeways and beltways and bridges and other high-use traffic channels along which flow swirling, never-ending currents of cars. Or from standard suburban development. Rock Creek is a complex example of how the city threatens its own amenities. We have glanced at it already--polluted by casual spurts and dribbles of waste from hundreds of thousands of people, its basic hydrology and therefore its very existence as a stream dependent on the proper use of the rural upper third of its watershed. For it has already suffered the loss of many tributary runs and branches in the lower two-thirds during the process of solid development.